1. Field of the Invention
This invention relates to methods and aparatus for (1) increasing the efficiency of a recoilless rifle and (2) making it feasible to mount a recoilless rifle on and fire a recoilless rifle from an aircraft.
2. Description of the Prior Art
A recoilless rifle balances recoil, i.e., provides counter-recoil action, by exhausting a portion of the powder gas rearwardly. To achieve a given muzzle velocity for a projectile of a given mass, a recoilless rifle requires a substantially larger amount of powder than does a conventional closed-breech gun. This is because that portion of the powder gas which is exhausted rearwardly is not available to drive the forward moving projectile from the barrel. It would be advantageous if less gas could be used to provide counter-recoil action. This would provide for either of two attractive alternatives. If one used the same amount of powder that is ordinarily used, one could make the jets in the breech (through which counter-recoil gas flows) smaller and, because more gas would be available to drive the projectile, this would cause greater muzzle velocity. On the other hand, one could utilize a smaller powder charge to achieve the same muzzle velocity as is presently achieved (again because the breech jets could be made smaller and a greater portion of the powder gas would be available to drive the projectile).
When a recoilless rifle is fired, the rearwardly directed counter-recoil gases produce what is known as the breech blast. Because of this breech blast, a recoilless rifle may not be mounted just anywhere on an aircraft. For example, if a recoilless rifle were mounted on the center-line of an aircraft, the breech blasts would expend against the fuselage and rupture it. A good description of this particular problem appears in U.S. Pat. No. 3,827,332 which issued to David B. Lindsay, Jr. on Aug. 6, 1974. Lindsay solves the problem by mounting the recoiless rifle on the tip of the aircraft wing so that the breech blast will be spaced far enough away from any part of the aircraft that it will be unable to do any damage. In certain situations, however, it would be advantageous to be able to mount a recoilless rifle on the center-line of an aircraft or at least in positions other than on the extreme wing tip.